1. Field of the Invention
The instant disclosure relates to a power semiconductor device; in particular, to a power semiconductor device having low on-state resistance for a power circuit.
2. Description of Related Art
Semiconductor packages are well known in the art. These packages can sometimes include one or more semiconductor devices, such as an integrated circuit (IC) device, die or chip. The IC devices can include electronic circuits that have been manufactured on a substrate made of a semiconductor material. The circuits are made using many known semiconductor processing techniques such as deposition, etching, photolithography, annealing, doping and diffusion. Silicon wafers are typically used as the substrate on which these IC devices are formed.
An example of a semiconductor device is a metal oxide semiconductor field effect transistor (MOSFET) device, which is used in numerous electronic apparatuses including power supplies, automotive electronics, computers and battery powered devices like mobile phones. MOSFET devices can be used in a variety of applications such as switches that connect power supplies to particular electronic devices having a load. MOSFET devices can be formed in a trench that has been etched into a substrate or onto an epitaxial layer that has been deposited onto a substrate.
MOSFET devices operate by applying an appropriate voltage to a gate electrode of a MOSFET device which turns the device on and forms a channel connecting a source and a drain of the MOSFET allowing a current to flow. Once the MOSFET device is turned on, the relationship between the current and the voltage is nearly linear which means that the device behaves like a resistor. For MOSFET devices, large RDS(on) may cause larger power consumption, and the RDS(on) of a transistor usually can be simulated and calculated. It is desirable to have low drain-to-source resistance RDS(on).
To reduce the drain-to-source on-resistance RDS(on) in MOSFET devices, numerous novel structures have been proposed and implemented.